<template>
  <div class="container">
    <!-- 固定导航 -->
    <van-nav-bar fixed left-arrow @click-left="$router.back()" title="小思同学"></van-nav-bar>

    <!-- 聊天主体区域 -->
    <div class="chat-list">
      <div v-for="(obj,index) in list" :key="index">
          <!-- 左侧是机器人小思 -->
          <div class="chat-item left" v-if="obj.name==='xs'">
            <van-image fit="cover" round src="https://img.yzcdn.cn/vant/cat.jpeg" />
            <div class="chat-pao">{{obj.msg}}</div>
          </div>

          <!-- 右侧是当前用户 -->
          <div class="chat-item right" v-else>
            <div class="chat-pao">{{obj.msg}}</div>
            <van-image fit="cover" round :src="useobj.photo" />
          </div>
       </div>
    </div>

    <!-- 对话区域 -->
    <div class="reply-container van-hairline--top">
      <van-field  placeholder="说点什么..." v-model.trim="word">
        <template #button>
          <span  style="font-size:12px;color:#999" @click="send">提交</span>
        </template>
      </van-field>
    </div>
  </div>
</template>

<script>
import { io } from 'socket.io-client'
import { mapState } from 'vuex'
let socket = null
export default {
  name: 'Chat',
  created () {
    // 创建socket实例化对象
    socket = io('ws://www.liulongbin.top:9999')
    //   建立链接,检测是不是成功
    socket.on('connect', () => {
      console.log(1)
    })
    // 监听服务器发来的信息
    socket.on('message', (data) => {
      this.list.push({
        name: 'xs',
        msg: data
      })
      this.$nextTick(() => {
        this.send()
      })
    })
  },
  activated () {
    // console.log(123)
    this.$nextTick(() => {
      //   this.scollinto()
      const doms = document.querySelectorAll('.chat-item')// 获取所有对话元素的伪数组
      const lastdom = doms[doms.length - 1]// 选择最后一个元素的dom
      lastdom.scrollIntoView({
        behavior: 'smooth'
      })
    })
  },
  beforeDestroy () {
    console.log('关闭')
    // 关闭连接
    socket.close()
    // 销毁 websocket 实例对象
    socket = null
  },
  data () {
    return {
      word: '', // 输入框的内容
      list: [// 所有的聊天消息
        // 1. 只根据 name 属性，即可判断出这个消息应该渲染到左侧还是右侧
        { name: 'xs', msg: 'hi，你好！我是小思' },
        { name: 'me', msg: '我是编程小王子' }
      ]
    }
  },
  computed: {
    ...mapState(['useobj'])
  },
  methods: {
    send () {
      if (this.word.length > 0) {
        socket.emit('send', this.word)
        this.list.push({ name: 'me', msg: this.word })
        this.word = ''
        this.$nextTick(() => {
          this.scollinto()
        })
      }
    },
    scollinto () {
      const doms = document.querySelectorAll('.chat-item')// 获取所有对话元素的伪数组
      const lastdom = doms[doms.length - 1]// 选择最后一个元素的dom
      lastdom.scrollIntoView({
        behavior: 'smooth'
      })
    }
  }
}
</script>

<style lang="less" scoped>
.container {
  height: 100%;
  width: 100%;
  position: absolute;
  left: 0;
  top: 0;
  box-sizing: border-box;
  background: #fafafa;
  padding: 46px 0 50px 0;
  .chat-list {
    height: 100%;
    overflow-y: scroll;
    .chat-item {
      padding: 10px;
      .van-image {
        vertical-align: top;
        width: 40px;
        height: 40px;
      }
      .chat-pao {
        vertical-align: top;
        display: inline-block;
        min-width: 40px;
        max-width: 70%;
        min-height: 40px;
        line-height: 38px;
        border: 0.5px solid #c2d9ea;
        border-radius: 4px;
        position: relative;
        padding: 0 10px;
        background-color: #e0effb;
        word-break: break-all;
        font-size: 14px;
        color: #333;
        &::before {
          content: '';
          width: 10px;
          height: 10px;
          position: absolute;
          top: 12px;
          border-top: 0.5px solid #c2d9ea;
          border-right: 0.5px solid #c2d9ea;
          background: #e0effb;
        }
      }
    }
  }
}
.chat-item.right {
  text-align: right;
  .chat-pao {
    margin-left: 0;
    margin-right: 15px;
    &::before {
      right: -6px;
      transform: rotate(45deg);
    }
  }
}
.chat-item.left {
  text-align: left;
  .chat-pao {
    margin-left: 15px;
    margin-right: 0;
    &::before {
      left: -5px;
      transform: rotate(-135deg);
    }
  }
}
.reply-container {
  position: fixed;
  left: 0;
  bottom: 0;
  height: 44px;
  width: 100%;
  background: #f5f5f5;
  z-index: 9999;
}
</style>
